To meet the demand for high areal density thin-film media and to improve the tribological performance of the head-disk interface, a certain amount of random or pattern roughness is applied to the surface of magnetic disks through the process of texturing. This texturing is applied to an annular head landing zone region on the surface of the magnetic disks. Texturing in the landing zone region is typically done prior to the deposition of sputtered layers.
The textured pattern can be generated through mechanical, chemical or laser techniques. The textured surface topography needs to be tightly controlled to ensure proper head-disk separation during head flying and good surface durability during head landing. Because it desired to minimize the percentage of the surface of the magnetic disk which is contacted by the head, the roughness takes the form of small discrete projections or bumps formed in the head landing zone region.
To reduce the head-disk contact area in the landing zone, the projection or bump size is minimized. This can be accomplished when the texturing is created using laser discharges by reducing the size of the laser beam which contacts the surface of the disk. Conventional laser beam spot size is usually less than 10 .mu.m in diameter, and is typically in the 5 to 8 .mu.m diameter range. The discharges are commonly separated by about 10 to 100 .mu.m. However, using a small beam spot size (less than about 10 .mu.m diameter) dramatically shortens the depth of focus of the laser beam and thus makes bump height difficult to control in the manufacturing environment. This is because the surface of the magnetic disk is not perfectly flat, but varies depending on small variations in the thickness of the magnetic disk and the degree of unevenness or waviness of the surface of the magnetic disk. Also, creating small diameter laser beams is itself somewhat difficult in a manufacturing environment.